plus (Struct)plus Struct

Objeto de función predefinido que realiza la operación de suma (operator+ binario) sobre sus argumentos.A predefined function object that performs the addition operation (binary operator+) on its arguments.

SintaxisSyntax

template <class Type = void>
struct plus : public binary_function <Type, Type, Type>
{
    Type operator()(const Type& Left, const Type& Right) const;
};

// specialized transparent functor for operator+
template <>
struct plus<void>
{
  template <class T, class U>
  auto operator()(T&& Left, U&& Right) const`
    -> decltype(std::forward<T>(Left) + std::forward<U>(Right));
};

ParámetrosParameters

Tipo, T, UType, T, U
Tipo que admite un operator+ binario que toma operandos de los tipos especificados o deducidos.A type that supports a binary operator+ that takes operands of the specified or inferred types.

IzquierdaLeft
Operando izquierdo de la operación de suma.The left operand of the addition operation. La plantilla no especializada toma un argumento de referencia lvalue de tipo Type.The unspecialized template takes an lvalue reference argument of type Type. La plantilla especializada realiza un reenvío perfecto de argumentos de referencia lvalue y rvalue de tipo deducido T.The specialized template does perfect forwarding of lvalue and rvalue reference arguments of inferred type T.

CorrectoRight
Operando derecho de la operación de suma.The right operand of the addition operation. La plantilla no especializada toma un argumento de referencia lvalue de tipo Type.The unspecialized template takes an lvalue reference argument of type Type. La plantilla especializada realiza un reenvío perfecto de argumentos de referencia lvalue y rvalue de tipo deducido U.The specialized template does perfect forwarding of lvalue and rvalue reference arguments of inferred type U.

Valor devueltoReturn Value

El resultado de Left + Right.The result of Left + Right. La plantilla especializada realiza el reenvío directo del resultado, que tiene el tipo devuelto por el operator+ binario.The specialized template does perfect forwarding of the result, which has the type that's returned by binary operator+.

EjemploExample

// functional_plus.cpp
// compile with: /EHsc
#include <vector>
#include <functional>
#include <algorithm>
#include <iostream>

using namespace std;

int main( )
{
   vector <double> v1, v2, v3 ( 6 );
   vector <double>::iterator Iter1, Iter2, Iter3;

   int i;
   for ( i = 0 ; i <= 5 ; i++ )
      v1.push_back( 4 * i );

   int j;
   for ( j = 0 ; j <= 5 ; j++ )
      v2.push_back( -2.0 * j - 4 );

   cout << "The vector v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")" << endl;

   cout << "The vector v2 = ( " ;
   for ( Iter2 = v2.begin( ) ; Iter2 != v2.end( ) ; Iter2++ )
      cout << *Iter2 << " ";
   cout << ")" << endl;

   // Finding the element-wise sums of the elements of v1 & v2
   transform (v1.begin( ), v1.end( ), v2.begin( ), v3.begin ( ), plus<double>( ) );

   cout << "The element-wise sums are: ( " ;
   for ( Iter3 = v3.begin( ) ; Iter3 != v3.end( ) ; Iter3++ )
      cout << *Iter3 << " ";
   cout << ")" << endl;
}
The vector v1 = ( 0 4 8 12 16 20 )
The vector v2 = ( -4 -6 -8 -10 -12 -14 )
The element-wise sums are: ( -4 -2 0 2 4 6 )